The methods and systems of the present invention are directed to the modification and improvement of transmissions for automotive vehicles of the type installed by the original equipment manufacturers. The invention is particularly directed to the improvement and modification of the automotive transmissions commonly known as the "4L80E" or the "Hydramatic 4L80E" which are "factory installed" in automotive vehicles manufactured by General Motors Corporation.
The present inventor owns U.S. Pat. No. 5,253,549, issued Oct. 19, 1993 and entitled "Methods And Systems For Improving The Operation Of Automatic Transmissions For Vehicles"; U.S. Pat. No. 4,790,938, issued on Dec. 13, 1988 and entitled "Filter For Removing Particulate Matter From Fluid Within A Movable Body"; U.S. Pat. No. 4,711,140, issued Dec. 8, 1987 and entitled "Throttle Valve System For Automatic Transmission"; U.S. Pat. No. 4,449,426, issued on May 22, 1984 and entitled "Laminated Separator Plate Means For Recalibrating Automatic Transmission"; U.S. patent application Ser. No. 08/333,552, filed Nov. 2, 1994 and entitled "Methods And Systems For Improving The Operation Of Transmissions For Motor Vehicles" (now U.S. Pat. No. 5,540,628, issued Jul. 30, 1996); U.S. patent application Ser. No. 08/494,844, filed Jun. 26, 1995 and entitled "Methods And Systems For Improving The Operation Of Transmissions For Motor Vehicles" (now U.S. Pat. No. 5,624,342, issued Apr. 29, 1997); U.S. patent application Ser. No. 08/515,098, filed Aug. 14, 1995 (now U.S. Pat. No. 5,730,685, issued Mar. 24, 1998) and entitled "Methods And Systems For Improving The Operation Of Transmissions For Motor Vehicles; U.S. patent application Ser. No. 08/595,810, filed Feb. 2, 1996 (now U.S. Pat. No. 5,743,823, issued Apr. 28, 1998) entitled "Methods And Systems For Improving The Operation Of Transmissions For Motor Vehicles"; U.S. patent application Ser. No. 08/697,625, filed Aug. 28, 1996 (now U.S. Pat. No. 5,768,953, issued Jun. 23, 1998) and entitled "Methods And Systems For Improving The Operation of Transmissions For Motor Vehicles"; and U.S. patent application Ser. No. 08/816,715, filed Mar. 13, 1997 (now U.S. Pat. No. 5,820,507, issued Oct. 13, 1998) and entitled "Methods And Systems For Improving The Operation Of Transmission For Motor Vehicles". The basic operation of transmissions for automotive vehicles is discussed in the aforementioned patents and patent applications, and these patents and patent applications are expressly incorporated by reference into the disclosure of the present patent application.
The basic principles of operation of the factory installed General Motors 4L80E transmission for automotive vehicles, including the specific modes of operation thereof and the hydraulic circuits and interrelationship of hydraulic circuits, are well known to those skilled in the automotive transmission art. Attention is respectfully invited to the operations manual and text entitled HYDRA-MATIC 4L80-E TECHNICIAN'S GUIDE (1990), published by General Motors Corporation, said publication describing in detail the operation of the "factory installed" 4L80E General Motors transmission, including a discussion of the structure, the hydraulic circuits, and the interrelationship between the structure and the hydraulic circuitry and fluid flow during normal operation of the transmissions in automotive vehicles. The disclosure of the aforementioned publication in its entirety is expressly incorporated by reference into the disclosure of the present patent application as disclosing and illustrating background material known to those of ordinary skill in the automotive transmission art.
In the original design of the 4L80E "factory installed" transmission, the first gear ratio cannot be obtained above a vehicle speed of approximately 35 miles per hour. (See the aforementioned General Motors Corporation publication). A primary object of the present invention is to enable the driver of a vehicle having a 4L80E General Motors transmission to select first gear at any time, thereby enabling the driver to obtain a "first" gear ratio whenever the gear selector lever is placed in the "1" position without regard to the actual vehicle speed and engine rotational speed. This objective is accomplished by modification of the structure and operation of the existing hydraulic circuits of the original transmission and the addition of a new hydraulic circuits to the original transmission.
It is also desirable to modify the "factory installed" automotive transmission to result in quick application during upshifts and quick release forces during downshifts with minimum ratio sharing (overlap) during gear changes, for improved performance particularly when the vehicle is operated at high performance conditions such as racing applications. This object is obtained by varying the structure and operation of the hydraulic circuits of the original transmission to enlarge or reduce existing orifices to control the apply and release fluid flow through the hydraulic circuits, in conjunction with the modification of different spring and pressure values of the pre-existing hydraulic circuits of the factory installed transmission.
Other objects, improvements and advantages of the present invention will become apparent to those skilled in the art from the following description in conjunction with the drawings.